Project Background/Rationale: Controlled prescription medication overdose, primarily from opioid analgesics (used to treat chronic pain) and/or benzodiazepines (used to treat posttraumatic stress disorder, or other anxiety or sleep disorders), is the leading cause of fatal injury in the United States. Veterans who use Veterans Affairs (VA) healthcare have twice the risk of medication overdose deaths than non-Veterans. Reasons for this increased risk are unknown, but theories include the unique health characteristics of Veterans (e.g., combat-related physical and mental health disorders) and/or prescribing practices among VA providers. It is also possible that Veterans who receive VA prescriptions simultaneously receive prescription medications from non-VA prescribers. State prescription drug monitoring programs (PDMPs) are available to help reduce prescription drug overdoses by providing data on dispensing of controlled medications across providers and systems. In 2013, the VA began allowing VA clinicians to query state PDMP data on VA patients. Our preliminary PDMP data show that a substantial proportion of Veterans prescribed opioids within the VA have also been prescribed opioids by non-VA prescribers. However, despite their access to the PDMP, very few VA prescribers use this important tool to review patients' prescription histories, leaving some Veterans at risk of potentially unsafe medication use. Project Aims: Our mixed-methods health services research project will evaluate the epidemiology of opioid, benzodiazepine, and other controlled prescription medication dual use (VA and non-VA) and all opioid-related adverse events (fatal and nonfatal; VA- and non-VA-treated) among the entire population of Iraq and Afghanistan War Veterans (OEF/OIF/OND) in Oregon, while simultaneously assessing barriers to PDMP use among VA clinicians. Specifically, our aims are to: (1) Quantify, and characterize patterns of, dual use of VA and non-VA prescribers of opioids and benzodiazepines among OEF/OIF/OND Veterans in Oregon; (2) Describe rates, types, and risk factors for all opioid/benzodiazepine-related adverse events among OEF/OIF/OND Veterans in Oregon; and (3) Identify barriers and facilitators to state PDMP use among VA opioid/benzodiazepine prescribers in Oregon. Project Methods: To accomplish Aims 1 and 2, we will link VA to multiple state (Oregon) databases to identify the full range of controlled prescriptions (VA and non-VA) that OEF/OIF/OND Veterans are receiving as well as their risk of overdose and other adverse events treated inside or outside the VA. This project will be the first to leverage VA, state PDMP, and state health surveillance databases to examine the full spectrum of opioid safety in a population-level cohort of Veterans. Data from 2011, the year the Oregon PDMP was implemented, through 2015 will be used to identify patterns, characteristics, rates, and risk factors for dual VA/non-VA prescriber use and, independently, opioid-related adverse events. Changes over time in prescribing/adverse events will be analyzed. To accomplish Aim 3, we will interview and survey VA prescribers about barriers and facilitators to using the Oregon PDMP, also examining changes over time relative to the implementation of VA medication safety initiatives. Results will lead to strategies for incorporating PDMP queries into VA clinical workflow. Although focused primarily on Oregon Veterans and prescribers, our work is in partnership with the National VA Program for Pain Management, helping ensure that results will maximally inform medication safety efforts across VAs nationally. Anticipated Impact: The VA is the largest provider of healthcare services to Veterans and serves some of the most at-risk Veterans in the US. Results of our research will provide crucial knowledge for VA prescribers and operations leaders to better address combat Veterans' medication safety. This project will help us better understand risk of dual use of VA and non-VA prescribers, the full range of adverse events related to opioids and benzodiazepines, and barriers to accessing and using PDMP tools among VA prescribers. This work will directly support interventions that improve clinicians' use of state PDMPs to inform prescribing decisions and, ultimately, reduce opioid-related adverse events among Veterans.